1. Field of the Invention
The present invention is generally related to a gas flow regulator and, more particularly, to a gas flow regulator that allows a microprocessor to accurately control the flow of a gas provided at an outlet of the regulator.
2. Description of the Prior Art
Those skilled in the art are familiar with many different types of regulators. When used in conjunction with nitrous oxide or gaseous fuels, such as liquefied petroleum gas (LPG), it is important that the gas is provided to a combustion chamber of an engine at an appropriate flow rate to result in the desired air/fuel ratio.
U.S. patent application Ser. No. 09/925,281, which was filed by Heffel et al. on Aug. 8, 2001, describes an apparatus and method for operating internal combustion engines from variable mixtures of gaseous fuels. The apparatus and method allow arbitrary mixture ratios of multiple fuel gasses having differing combustion characteristics, such as natural gas and hydrogen gas, to be used in an internal combustion engine. The gaseous fuel composition ratio is first sensed, such as by thermal conductivity, infrared signature, sound propagation speed, or equivalent mixture differentiation mechanisms and combinations thereof which are utilized as inputs to a multiple map engine control module which modulates selected operating parameters of the engine, such as fuel injection and ignition timing, in response to the proportions of fuel gases available so that the engine operates correctly and at high efficiency irrespective of the gas mixture ratio being utilized. As a result, an engine configured according to the teachings of this invention may be fueled from at least two different fuel sources without admixing constraints.
U.S. Pat. No. 6,131,552, which issued to Paielli et al. on Oct. 17, 2000, describes a fuel control system for a gas-operated engine. The system relates to the delivery of gaseous fuel from a source through an air/fuel mixture to a gas-operated engine that includes at least one sensor for operative coupling to the engine to provide at least one electronic sensor signal responsive to engine operating conditions. An electronic control unit is responsive to the sensor signals for providing a fuel control signal indicative of a desired quantity of fuel to be delivered to the engine. A pressure regulator, for disposition between the fuel source and the fuel/air mixture, is responsive to the fuel control signal for controlling delivery of gaseous fuel to the mixer. The pressure regulator includes a housing having an inlet for connection to the fuel source and an outlet for connection to the mixer. A valve is disposed within the housing and biased toward closure by a primary pressure regulating spring for controlling flow of fuel from the inlet to the outlet. A solenoid force motor is mounted on the housing and has a force coil for receiving and translating the fuel control signal. A rigid actuating member is driven by and extends from the coil into the housing directly to the valve actuating lever for modulating control of the operative position of the valve in bypass mechanical force transmission relationship to the regulating spring, and thereby modulating control flow of gaseous fuel through the housing, as a function of the fuel control signal to the pressure regulator.
U.S. Pat. No. 6,026,787, which issued to Sun et al. on Feb. 22, 2000, described an air-fuel control for alternative engine fuels. A mixture of gaseous fuel, such as natural gas or propane, and gasoline is used to fuel the internal combustion engine of a motor vehicle. The ratio of gaseous fuel to gasoline is preadjusted by the manual settings of an electronic processor which is used to change the gasoline fuel injection rate and the manual settings of a air/vacuum balance valve connected to a low pressure regulator and mixer are used to regulate the pressure of the gaseous fuel and mix it with air to provide the desired ratio. The fuel injection is also controlled in response to a signal fed to the processor which is in accordance with the output of the vehicle's exhaust oxygen sensors. The flow rate of gaseous fuel to the engine is controlled by means of a mixer which is preadjusted for a desired flow rate. This flow rate is automatically varied in response to the intake manifold pressure of the engine. This manifold pressure drives a valve which controls the gaseous fuel flow rate. When one of the dual fuels is depleted, a control in the electronic processor operates to switch to the other fuel and the vehicle is then operated on a single fuel.
U.S. Pat. No. 5,860,407, which issued to Chapin et al. on Jan. 19, 1999, describes a gaseous fuel control system for engines. It is a system for delivering and regulating fuel and air flows to the engine and an electronically controlled rotary pressure regulator implementing fine adjustments in the pre-mixing pressure of gaseous fuel. Gaseous fuel from a high-pressure fuel tank is forced into a passage and through a series of pressure regulators during combustion. Inside the throttle body, butterfly plates respond to signals from an electronic controller to regulate the flows of air and gaseous fuel. The fuel passes into a stagnation chamber and mixes with air flow through a series of radial mixing orifices in a common wall between the stagnation chamber and the air passageways. The fuel/air ratio is coarsely controlled by the reaction of the butterfly plates to the signals of the electronic controller and is more finely controlled by electronic rotation of the rotary gas pressure regulator.
U.S. Pat. No. 5,551,407, which issued to Greenway on Sep. 3, 1996, describes a fuel-air mixer apparatus and method for gaseous fuel engines. A fuel-air mixer body includes a mixer passage extending therethrough with a fuel release body positioned centrally within the mixer passage. A fuel control section of the mixer passage is defined between the inner wall of the mixer passage and the outer wall of the fuel release body, and includes a flow restricting section and a flow area increasing section. As input air to be mixed with fuel for combustion flows through the mixer passage, a relatively high pressure area is formed in the flow restricting section, a first pressure reduction area is produced in the flow area increasing, and a second pressure reduction area is produced downstream from the fuel release body. Gaseous fuel may be released into the air at two separate locations. The first location is in the flow area increasing section and the second location is at the end of the fuel release body. The method of the invention includes producing the relatively high pressure area within the mixer passage, to separate reduced pressure areas within the passage, and releasing gaseous fuel in the two reduced pressure areas to produce the desired fuel-air mixing.
U.S. Pat. No. 5,337,722, which issued to Kurihara et al. on Aug. 16, 1994, describes a fuel control and feed system for a gas fueled engine. Several embodiments of engines and systems for fueling engines to reduce the emission of unwanted exhaust gas constituents are described. These embodiments also improve the fuel economy of the engine. A catalytic converter is provided in the exhaust system and a gaseous fuel is used at least during starting so as to bring the catalytic converter up to its operating temperature rapidly without necessitating the provision of an enriched fuel/air mixture. An oxygen sensor is employed in the exhaust system and a feedback control system varies the fuel/air ratio of the engine during its running in response to the output of the oxygen sensor. In order to test that the oxygen sensor is at its operating condition before feedback control is initiated, a rich fuel mixture is supplied and this rich fuel mixture is discontinued immediately upon the receipt of a signal from the oxygen sensor indicating that a rich mixture exists. Applications of the principal to both air valve type of carburetors and conventional carburetors are disclosed.
U.S. Pat. No. 5,251,602, which issued to Kurihara et al. on Oct. 12, 1993, describes a fuel supply system for gas-fueled engines. Two embodiments of air/fuel ratio adjusting systems for gaseous fueled internal combustion engines are described. In each embodiment, a pressure regulator supplies regulated fuel in gaseous form from a source in which it is stored in a liquid from to a charge former that has a fuel control device such as a needle valve. The air/fuel ratio is maintained constant by mixing atmospheric air with the fuel before the charge former fuel control device under the control of the oxygen sensor in exhaust system. In one embodiment, an enrichment system is also incorporated for supplying enrichment fuel under acceleration or cold starting conditions.
U.S. Pat. No. 4,497,304, which issued to Wintrell et al on Feb. 5, 1985, describes a fuel and air mixing apparatus. The invention comprises a system for introducing gaseous or vaporized fuels into a carburetor from a storage tank including a regulator connected between the tank and the carburetor for providing a supply of hydrocarbon fuel in a gaseous state at a regulated vapor pressure to a mixing chamber having air and fuel intake ports to blend the hydrocarbon fuel with intake air for injection into the carburetor. In a typical installation, the pressure change of the vacuum manifold alters the pressure within the mixing chamber to draw in fuel and air in proportion to a near constant equivalence ratio, due to the respective areas of the intake ports, over the entire operating range of the engine. U.S. Pat. No. 4,413,607, which issued to Batchelor et al. on Nov. 8, 1983, described a propane carburetion system. The system is used with an existing combustion engine. It provides for enabling the engine to be operated on a liquefied propane, alone, through a conventional gasoline carburetor, to operate on either gasoline or liquefied propane through a conventional gasoline carburetor, to operate on liquefied propane, alone, through an inlet casting to be utilized in lieu of a conventional gasoline carburetor, or to operate on liquefied propane, alone, at a substantially constant engine speed. Further, the system is also operative in conjunction with a diesel engine whereby a small amount of gasified liquid propane may be introduced into the induction system of a diesel engine as a supplemental fuel charge therefore during high power demand periods of operation. The system includes a regulator-vaporizer assembly for reducing the pressure of and thus transferring liquid propane into gasified liquid propane, heating the propane gas and ducting the propane gas to an induction passage mixer, the latter including various adjustment features whereby the proper mixture of induction air and propane is afforded.
U.S. Pat. No. 4,112,889, which issued to Harpman on Sep. 12, 1978, describes a fuel system and vaporizer for internal combustion engines. A fuel system for an internal combustion engine of the piston type vaporizes a liquid fuel and water and mixes the resulting gaseous fuel and water vapor with air in a metering valve which communications with the internal combustion engine. A device operating at a very high temperature is used in the vaporization of the fuel. The high temperature gaseous state of the fuel represents molecules of the greatest degree of separation from each other providing the greatest opportunity for contact of the reacting species in the gaseous condition as chemical reactions occur only between particles at the atomic or molecular level and it is necessary for the reacting special to be in actual contact at the time of reaction. The fuel system therefore enables complete combustion and elimination of the atmospheric pollutants common in the operation of internal combustion engines.
U.S. Pat. No. 3,650,254, which issued to McJones on Mar. 21, 1972, describes a method and apparatus for rapidly changing the air-fuel ration of an internal combustion engine from a lean condition to a rich condition. A regulator in the fuel system of a vehicle's internal combustion engine regulates the fuel pressure of a gaseous fuel, such as natural gas, to a fuel-air mixer. The regulator maintains a predetermined fuel pressure for idle and cruise conditions and increases fuel pressure to effect an enriching of the air-fuel ratio for full throttle conditions. The degree of enriching is sufficient to pass through a region where there is a threat of exhaust valve burning and where the maximum amount of the oxides of nitrogen are produced. The change in air-fuel ration is extremely rapid to avoid operation for any material amount of time in this region. The regulator also effects a change from a rich air-fuel ratio to a lean one at a predetermined point in throttle setting below the point at which enriching occurs. Most currently known gaseous fuel pressure regulators are unable to achieve the accurate regulation of gaseous fuel pressure needed to rapidly control the gaseous fuel pressure during significant load or speed transients. As a result, significant deviations of air/fuel ratios from desired air/fuel ratios can occur. When these deviations occur, they can represent a significant degradation of both emissions and running quality of the engine.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.